Lithium remains one of the most effective treatments for bipolar disorder, but a major new study shows that nearly 6 in 10 long-term users experience accelerated kidney decline. Researchers from the Netherlands tracked 196 bipolar patients over a decade and found that kidney function deteriorated significantly faster in those taking lithium compared to the general population, prompting difficult conversations about balancing mental health stability with organ damage.

How Does Lithium Affect Kidney Function Over Time?

The Dutch study measured kidney health using a standard test called estimated glomerular filtration rate (eGFR), which shows how well kidneys filter waste from the blood. Researchers followed patients for a median of 8.8 years and discovered a statistically significant decline in kidney function across the group. The median kidney function dropped by 0.79 mL/min/1.73 m² per year, but the concerning part was that 11% of participants experienced much steeper declines, losing more than 2.5 mL/min/1.73 m² per year.

The study found a clear relationship between how much lithium was in patients' bloodstreams and how quickly their kidneys declined. Patients who had been on lithium longer, with a median duration of 16 years, showed greater kidney function loss. When researchers compared the lithium group to the general Dutch population, the difference was stark: 59% of lithium users had faster kidney decline than what would be expected in people not taking the medication.

What Happens When Patients Stop Taking Lithium?

One of the most important findings involved patients who discontinued lithium during the study. Of the 196 participants, 39 stopped taking the medication. In 18 cases, the reason was documented side effects, including kidney damage, excessive urination (a known lithium side effect), or because their psychiatric symptoms had improved. When researchers tracked what happened to kidney function after patients stopped lithium, they found the decline slowed from 1.3 mL/min/year to 0.27 mL/min/year. However, this improvement was not statistically significant during the study period, possibly because the follow-up time was too short or the group was too small to detect meaningful change.

This finding matters because it suggests that stopping lithium might help protect remaining kidney function, but the benefit may take years to become apparent. For patients already experiencing kidney damage, the question becomes whether the mental health benefits of continuing lithium outweigh the risk of further organ deterioration.

Key Factors That Influence Kidney Decline in Lithium Users

• Lithium Concentration: Higher levels of lithium in the bloodstream were directly associated with faster kidney function decline, suggesting that lower therapeutic doses might reduce kidney risk.
• Duration of Treatment: Patients who had taken lithium for longer periods experienced greater kidney function loss, with the median duration in this study being 16 years of continuous use.
• Age and Sex: Researchers controlled for these factors in their analysis, finding that the kidney decline was linked to lithium exposure itself rather than patient demographics alone.
• Other Medications: The study found no significant evidence that other kidney-damaging medications made the lithium-related decline worse, though researchers noted more research is needed on this question.

Why This Matters for Bipolar Disorder Treatment

Lithium has been a cornerstone of bipolar disorder treatment for decades because it is unmatched in its ability to stabilize mood and reduce hospitalizations. However, its impact on kidney health has long been a concern for patients and doctors alike. This new research quantifies that concern in concrete terms, showing that the risk is real and measurable over time.

For patients living with serious mental illness, the choice between mental health stability and physical health is not theoretical. As one researcher noted in the study commentary, patients with bipolar disorder are not passive observers of their treatment; they have serious stakes in the outcome. The study emphasizes that this is not a simple question with an obvious answer, which is why ongoing monitoring and individualized treatment planning are essential.

What Should Patients and Doctors Do Now?

The research team acknowledged several limitations in their study. As an observational study, it cannot prove that lithium directly causes kidney decline, only that the two are associated. The researchers also could not verify whether patients waited the required 12 hours after taking lithium before blood tests were drawn, which could affect measurements. Additionally, the study did not examine whether other health conditions like diabetes or high blood pressure might be contributing to kidney decline alongside lithium use.

Despite these limitations, the findings reinforce current clinical practice: patients on long-term lithium should have their kidney function monitored regularly through blood tests. The study suggests that doctors and patients should discuss the risks and benefits openly, consider whether lower doses might be effective, and explore whether alternative treatments might be appropriate for some patients. For those who continue lithium because it is the most effective treatment for their bipolar disorder, regular monitoring allows doctors to catch kidney problems early and make adjustments before serious damage occurs.

The research also points to the need for larger, longer studies that include information about other health conditions and medications, so that doctors can better understand which patients face the highest kidney risk and how to minimize harm while maintaining mental health stability.